Cast articles are generally produced by forming a mold having a cavity therein with molding sand based on a wooden or metal pattern, optionally introducing a core to the cavity, and pouring molten metal into the cavity.
A sand mold is produced with molding sand by adding usual sand and a binder for hardening the sand to retain a shape, and thus used sand requires a reconditioning process for recycling. Further, there is a problem of generation of waste material such as dust during the reconditioning process. In the case of using a core of sand mold, in addition to the problem, there are problems of difficulty in handling the core due to a weight of the core itself and requirement of contradictory performances of strength retention during casting and removability of the core after casting.
To solve such problems, those techniques have been known, including a method for producing a structure for producing cast articles containing organic fibers, inorganic fibers, inorganic particles and a thermosetting resin, which the structure is lightweight, has good processability, and reduces waste (JP-A 2005-349428, WO-A 2005/120745, EP-A 1 754 554).
JP-A2007-144511 discloses a structure for producing cast articles containing flake graphite having an average particle diameter of 70 μm or less, a thermosetting resin and organic fibers.
JP-A 62-45446 and JP-A 62-156044 disclose materials for shell molds containing sand coated with a thermosetting resin and hydrated magnesium silicate clay mineral.
GB-A 1281684 (JP-B 50-20545) discloses a heat insulating body used for casting molten metal and describes a gas permeability thereof.